Mother and father are bickering over deadbeat son who refuses to leave the family home (pays not rent, buys no food, etc.) despite being order to leave by his father, yet refuses. The father files for eviction through the court system, will eviction work in a community property state

It depends who is at what location when various events occur.

Dad could file for eviction. If Mom shows up at court hearing, proves that she is part owner and son is HER invited guest the judge would probably dismiss the whole thing at that point.

Even if Dad slipped the whole eviction process past Mon and got Son thrown out, I believe she could just invite him back to the property and start the whole ball rolling all over again.